The present invention relates to a multiple-ink-jet plotter or printer.
There have been devised and demonstrated various types of ink-jet printers or plotters. In one type, a binary or nozzle-per-spot print head or a single nozzle, electrostatic deflection type print head is mounted on a carriage which is moved relative to a recording medium. Whenever the carriage reaches either end of one printing line, the recording medium is displaced or fed by one spacing in the direction perpendicular to the movement of the carriage. In practice, the nozzles are varied in nozzle hole diameter from one to another and the pressure applied to the ink in the ink manifold or the like varies from one to another, all of the print head units must be adjusted individually so that a uniform dot spacing may be obtained. Otherwise, the spacing between the ink dots printed by the adjacent ink-jet print head units varies or the spacing between the array of ink dots printed by one stroke of the print head and the array of ink dots printed by the next stroke of the print head becomes too wide or too short, leaving a blank column or row or a black line segment due to the partial overlapping of the ink dots in the outermost columns or rows of the adjacent ink dot arrays. As a result, the overall image quality is considerably impaired. This defect is also caused by the aging of the ink which is recirculated and/or by the variations of the driving voltages applied to respective print head units.